For millions of European voters, the experience of governments identified with the left have in the past decade become increasingly indistinguishable from the authoritarian neoliberalism of the new right. In France, the retreat from social democracy has been more gradual, buttressed by the influence of the Communist party (one of the main political forces until the 1980s), strong social movements and the institutional gains of the postwar era. But just as 1979 was Britain's electoral crossroads, the 2007 presidential election threatens to do the same for France.

The choice is between the populist free-market authoritarianism of Nicolas Sarkozy, the rightwing frontrunner, and the social Blairism of Ségolène Royal, the Socialist party candidate - with the threat of the far-right Jean-Marie Le Pen in the background. Whichever way you look at it, the right will stay in office in some form. The "anti-liberal" coalition (as opposition to neoliberalism is called) draws in radical parties and social movements to the left of the Socialists, but has been unable to rally round one candidate for April's election. Its failure could even pave the way for the kind of political and economic restructuring Britain experienced under Thatcher.

The left's problem is not lack of popularity. In the 2002 election, the three main candidates of the left and the Greens combined polled 18.5% of the vote (compared with 19.8% for Jacques Chirac and 16.8% for Le Pen). It is the fragmentation of the vote that is damaging, particularly in the face of a resurgent European right. The victorious 'no' campaign against ratification of the EU constitution in 2005 cemented a longstanding feeling that the "anti-liberal" left needed a single candidate for this year's presidential elections.

The anti-liberal coalition has been forged in the heat of successive social struggles over the past 10 years: the campaigns of les sans, and the movements against social security, pension and labour market reforms, and against the EU constitution. This momentum has been nurtured by a grassroots alliance of political organisations (communists, other leftwingers and environmentalists), social movements, trade unions and activist groups, with more than 700 local collectives operating across France.

Having worked out a common strategy and programme for government, all the coalition had to do was agree on a candidate. But last month it splintered, and the historic chance to have its say was gone.

"It's not unrealistic to think that we would have seriously challenged the Socialist party," said Yves Salesse, one of the architects of the united front. "Many of our proposals, whether the struggle against privatisation, American imperialism or GM food, resonate with the majority in the country."

However, although activists still want to convert dynamic social campaigns into success at the ballot box (just as in Britain Respect has sought to capitalise on the anti-war movement), the coalition's unity has foundered on the hidebound political culture of the leadership of the radical left's main players, the Communist party and the Revolutionary Communist League. More concerned with party apparatus and old feuds, both have proved incapable of adopting a consensual approach to providing an alternative to the Socialist party.

France's recent past demonstrates that it is the social movements (students, unions, les sans, feminist and environmental groups) that have had most impact, providing a genuine counterweight to neoliberal policies. When last year Sarkozy announced a new hardline bill on immigration, local and national collectives mobilised to oppose a project aimed at dividing "good foreigners", of benefit to the economy, from "bad foreigners", those seen as a burden on the republic.

Current campaigns against deportations would never have taken off without the battles of les sans. An opinion poll last October suggested 73% of French people were in favour of regularising the sans-papiers who had children in France or a work contract. But the role of political parties in changing opinion has been at best marginal.

Likewise, the huge response generated by the individuals who called on people to sleep on the streets of Paris in solidarity with the homeless has panicked the political establishment. In his end-of-year speech, Chirac was obliged to highlight housing, and the government recently announced emergency measures.

For many activists, the failure of the coalition to agree on a presidential candidate will strengthen the belief that sinking resources into electoral strategies is, for the meantime at least, a diversion. It seems more effective to them to devote their energies to building networks and movements, starting from concrete situations and without a preconceived model, which can change politics and society from below.

· Naima Bouteldja, a French journalist, is a researcher for the Transnational Institute. A longer version of this article appears in next month's Red Pepper naima.bouteldja@gmail.com